To study the traffic efficiency in one-way restricted waterways, this article analyses the mechanism of vessel deceleration caused by the interference of the vessel domain and presents a model of vessel deceleration distance and a model of vessel deceleration condition based on traffic flow characteristics. In addition, a simulation model was applied to sensitivity analysis of five interference factors with impacts on traffic efficiency. The results show that the vessel standard deviation is the most sensitive factor when considering the vessels' negative acceleration.
With the rapid development of the global economy and vessel technology, vessels are becoming larger, and their velocities have increased. The original unique waterways are increasingly unable to meet the navigation needs of large-scale vessels, and water traffic is becoming more congested. Even worse, some of the waterways have even become restricted waterways. When navigating in one-way restricted waterways, the rate of vessel encounters between large-scale vessels will increase, vessel safety domain will be affected by the difference in speed with adjacent vessels, and vessel deceleration and other problems of traffic efficiency will become increasingly prominent. At present, research on traffic efficiency in restricted waterways has mainly focused on the characteristics and the simulation of vessel traffic flow and the evaluation of traffic efficiency. The main results are as follows:
(a) Research on vessel traffic flow.
The early research on the characteristics of vessel traffic flow mainly focused on the queuing theory, which suggests that vessel arrival followed a certain distribution and that the time for vessels entering into the waterways could be ascertained according to the safety navigation rules and requirements. However, queuing theory ignored the vessels’ interactive behaviour in the waterways, such as the collision avoidance behaviours taken by the vessels. In recent years, scholars have proposed a vessel coordination theory based on the queuing theory. They carried out simulation analyses on the typical restricted waterways, such as the intersections of waterways. There were also empirical simulation models for estimating the safe distance between vessels based on the actual situations. Based on the characteristics of traffic flow, Chen (2012) analysed the changes of vessel traffic flow and vessel speed distribution over the Yangtze River, and verified that there was a close relationship between vessel traffic flow, vessel speed and vessel density. Combined with the actual data, Tan (2010) used the method of a twosided test to analyse the distribution of vessel arrival in the waterway of the Jinzhou Changjiang Bridge, and the results assured that the vessel arrival followed a Poisson distribution.
